The pneumatic tire has proven to be a preferred means of realizing a comfortable ride on any number of vehicles, such as bicycles, automobiles, trucks, and aircraft. However, pneumatic tires by their very nature are prone to becoming flat. In urban driving conditions, flats are usually brought about by excessive wear or some sort of puncture injury. Ordinarily a flat usually means stopping the vehicle and fixing or replacing the flat. In more challenging road conditions, such as those encountered in combat situations, stopping the vehicle to subsequently fix or replace a flat may not be an option and a more viable option is to simply drive away from the threat zone so that the compromised tire can be subsequently fixed or replaced in relative safety.
A tire capable of safely running over a certain distance without losing its ability to bear the load of the vehicle even if internal air pressure of the tire is reduced due to being compromised is understood to be a run-flat tire. It is preferable that when the run-flat tire is not compromised, i.e., inflated, then it should not overheat and not unnecessarily strain the suspension. It is also preferable in the event that the run-flat tire is compromised, i.e., deflated, it is able to withstand the load of the vehicle by being sufficiently flexible so that it does not strain the vehicle suspension providing a relatively comfortable ride while maintaining continuity at the bead seat/rim interface. This continuity must be maintained to prevent the tire from coming off the rim and stopping the vehicle.
Solid polyurethane tires have been used in industrial applications including forklift drive/load wheels and in off-the-road applications in the construction, lawn/garden and ground support equipment industry. Other polyurethane tire construction variants are used on wheelchairs, bicycles and in like wheel applications. However, solid polyurethane tires have proven to be not entirely satisfactory because they do not exhibit adequate cushioning and their handling characteristics are oftentimes not desirable. Solid polyurethane tires also suffer from unacceptable internal heat build-up and subsequently are prone to degradation during prolonged vehicle high speed service conditions.
An example of a disclosure for producing deflation proof pneumatic tires from a variety of compositions can be found in U.S. Pat. No. 6,629,550 which is incorporated by reference herein.
Pneumatic tires on combat vehicles can be flattened by any number of different ways, e.g., spikes, rifle shots, and improvised explosive devices (IEDs). It is preferable to design tires for combat vehicles so that they are at least resilient against being immediately disabled. A ballistic resilient run-flat tire would allow the injured combat vehicle to either maneuver into a defense position or to exit the threat zone.
Beyond the dangers of IEDs, combat vehicles, are also vulnerable by being stuck within a combat zone due to their tires being flattened by calibers such as 7.62-39 mm and 7.62×54 R rifle shots.
Accordingly, a ballistic resilient run-flat tire would be a desirable combat or law enforcement vehicle feature providing the tire could allow a vehicle to rapidly speed away with a complete loss of tire air pressure (e.g., 30 mph) from the threat to a considerable safe location (e.g., at least 30 miles).
Accordingly, a need exists for a ballistic resilient run-flat tire capable of traveling for a relatively long distance for at least 30 miles away from the ballistic incident site.